Electric switch



Patented Nov. l, 1932 PATENT OFFICE rnancnsco rEnnoTTI, or MILAN, ITALY ELECTRIC SWITCH Application illed July 15, 1930, Serial No. 468,169, and in Germany December 19, v1929.

' the provlsion of a switch operating within a gas-filled enclosure which, in the majority of cases, will not require the use of compressed gasv and even when the voltage on the circuitis very considerable only requires the use of a gas subject to a relatively small pressure which is easy to produce and maintain.

Hitherto no satisfactory .means for preventing the ready occurrence of discharge in compressed gases, on the interruption of the current circuit, has been found, nor has it `been found possible to make this discharge less marked'. Experiments Agive rise to the assumption that such behaviour depends mainly upon the reduction in the speed of 4 movement of the ions which is produced by the compression. f

According tothe present invention a high tension electric switch is constructed within a chamber iilledwith a gas at low pressure having a speed of ionic movement capable of providing similarl conditions to those of gaseous fluid in like circumstances, but at a higher pressure. Preferably the gas which is employed within the enclosure containing the switch contacts has, at the maximum pressure allowable, the same speed oi ionic movement as that which air would have when compressed to the pressure necessary to attain a satisfactory break of the circuit in air.

The single figure of the accompanying drawing is a schematic vertical section of one formof apparatus in which the invention can be carried out.

Referring to said drawing, the switch, of

appropriate type, is represented schematically by thefixed terminals l--2, which co-v operates-with a connecting bar 3, controlled from the outside by means of a movable device 4-5-6, disposed within a closedy recep- 55 tacle 7, provided With a nipple 8 through which the gas to be employed can be introduced, and with a :nanometer 9 which enables the pressure of the gas to be watched. All these parts can be constructed and arl ranged in any suitable manner, according to each special case to be considered; the invention relating exclusively to the chemical and physical nature of the gas introduced into the receptacle, according to the results 05 sought to be attained, independently of the nature and operation of the apparatus.

Preferably the gas to be employed is an organic compound possessing a molecular weight which is greater than 30. The speed of'movement of the ions is, as is known, determined in terms of the velocity in centimetres per second which the ions attain when they are subjected to the action of an electric iield of one volt per centimetre. The velocity varies with the temperature and pressure and has a characteristic value for every gas. In the case of dry air at 15 C. and 760 mm., the average velocity of movement of the ions is equal to K= 1.62.

Experiment shows that the velocity of movement of the ions in the case of different substances is dependent upon their molecular weights in accorance with a complex law, and in the case of organic gases is approximately in the inverse ratio to the 0.7 pow`er of the said molecular weight. In every gas the velocity of movement becomes less with increasing molecular weight and it is less than l in almost all organic gases, since all these have a molecular Weight greater than 30.4 If such gases as are used possess at normal pressure a travel speed which is less than l, then they will behave like compressed air at 1.6 atmospheres. If, for example, one uses vapors of carbon tetrachloride for which K=0.3 then one obtains the sameveifect as in the case of air at 5 atmospheres pressure.

A number of substances having desirable electrical characteristics and suitable for use pressure a middle specific mobility ofthe in accordance with this invention may be ions approximating 0.3.v found in a table appearing on page 125 ofy l In testimony whereof I aliix my signature. Conduction of Electricity through Gases by 5 Thomson,l3rd edition. FRAHNCESCO PERROTTI. 7o

When selecting the gasto be employed, its physical and chemical properties are, naturally, considered, and those for example which are poisonous as well as those which dissociate or which may attack metals will be rejected. Also those which for any other technical reason are unserviceable will be rejected although they may have a molecular weight higher than 30, and in every case an examination will be made in order to see if the 3f,

Vspeed of ionic movement of the gas to be used for the purpose in view is suiiciently higher than that of air in order to obtain the contemplated reduction of pressure.

What I claim is:

1. A high tension electric switch, comprising a gas-tight chamber enclosing the electrodes of the switch, the chamber containing a gas which has a middle specific mobility of the ions lower than 0.8. 90'

2. A switch as set forth in claim 1, the as within the chamber comprising a gaseous yn, drocarbon compound having a molecular weight higher than 30.

3. Means for extinguishing an electrical 95 arc comprising a gas surrounding the arc, said gas having at atmospheric pressure a middle specic mobility of the ions lower than 0.8. 4. Means for extinguishing an electrical im arc comprising a gas surrounding the arc, said gas comprising a gaseous hydrocarbon compound having a molecular weight higher than 30 and having at atmospheric pressure a 40 middle specific mobility of the ions lower '10:

than 0.8.

5. Means for extinguishing an electrical arc comprising a gas surrounding the arc, said gas having at atmospheric pressure a A middle specific mobility of the ions approx- 'Hi imat'ing 0.3.

6. An apparatus for drawing and extinguishing anvelectrical arc comprising electrodes, a gaseous medium surroundingJ the electrodes, said gas having at atmospheric pressures. middle specific mobility of the ions lower than 0.8.

7. An apparatus for drawing and extinguishing an electrical arc comprising e1ec` mt.

trodes, a gaseous medium surrounding the electrodes, said gas comprising a gaseous hydrocarbon compound having a molecular weight higher than 30 and having at atmol spheric pressure a middle specific mobility of 12 Ythe ions lower than 0.8. 4

" 8. A11 apparatus for drawing and extinguishing anelectrical arc comprising electrodes, a gaseous medium surroun the 55 electrodes, said gasrhaving at diggin-ic le.; 

